An eyewitness tells E! News that Martin stayed shielded behind a curtain throughout the signing and didn't engage with the crowd.

Then just yesterday morning, the formerly coupled duo were spotted riding the subway together in the Big Apple.

One rider tells E! News, "It was around 5:30 p.m. and I got on the train at Herald Square and saw them standing at the end of the car. No one else seemed to notice who they were—of if they did—they left them alone."

Our source says that while the two "seemed happy," things "didn't look romantic between them, just family-like."

"The truth is...well, I don't really love talking about this stuff," Martin said during an interview with the Valentine in the Morning radio show. "But the thing we told everyone at the beginning of the year is true. We are very close. We are not together. But we're, you know, that's the truth and that's it."

He continued, "You know, there's a lot of love. No scandal, I'm afraid. I wish I could give you scandal."